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Microstructure and Mechanical Properties of a Single Crystal NiAl Alloy with Zr or HF Rich G-Phase Precipitates.

Published online by Cambridge University Press:  26 February 2011

I. E. Locci ,
R. D. Noebe ,
R. R. Bowman ,
R. V. Miner ,
M. V. Nathal  and
R. Darolia
I. E. Locci
Affiliation:
NASA Lewis Research Center, MS 105–1, Cleveland, Ohio 44135
R. D. Noebe
Affiliation:
NASA Lewis Research Center, MS 105–1, Cleveland, Ohio 44135
R. R. Bowman
Affiliation:
NASA Lewis Research Center, MS 105–1, Cleveland, Ohio 44135
R. V. Miner
Affiliation:
NASA Lewis Research Center, MS 105–1, Cleveland, Ohio 44135
M. V. Nathal
Affiliation:
NASA Lewis Research Center, MS 105–1, Cleveland, Ohio 44135
R. Darolia
Affiliation:
GE Aircraft Engines, Cincinnati, Ohio 45215
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Abstract

The possibility of producing NiAl reinforced with the G-phase (Ni16X6Si7), where X is Zr or Hf, has been investigated. The microstructures of these NiAl alloys have been characterized in the as-cast and annealed conditions. The G-phases are present as fine cuboidal precipitates (10 to 40 nm) and have lattice parameters almost four times that of NiAl. They are coherent with the matrix and fairly resistant to coarsening during annealing heat treatments. Segregation and non-uniform precipitate distribution observed in as-cast materials were eliminated by homogenization at temperatures near 1600 K. Slow cooling from these temperatures resulted in large plate shaped precipitates, denuded zones, and a loss of coherency in some of the large particles. Faster cooling produced a homogeneous fine distribution of cuboidal G-phase particles (≤10 nm) in the matrix. Preliminary mechanical properties for the Zr-doped alloy are presented and compared to binary single crystal NiAl. The presence of these precipitates appears to have an important strengthening effect at temperatures≥1000 K compared to binary NiAl single crystals.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 213: Symposium Q – High-Temperature Ordered Intermetallic Alloys IV , 1990 , 1013
Copyright
Copyright © Materials Research Society 1991

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References

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